Aspirational examples for app developer contract.

aspirational_examples/04_composition_and_context.rs

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+//! Aspirational RUIN app API for composition, typed context providers, and app-wide services.
+//!
+//! Intentionally non-compiling; this is a design sketch.
+
+use ruin::prelude::*;
+
+#[ruin_runtime::async_main]
+async fn main() -> ruin::Result<()> {
+    App::new()
+        .window(Window::new().title("RUIN Workspace").size(1400.0, 900.0))
+        .mount::<WorkspaceRoot>()
+        .run()
+        .await
+}
+
+#[component]
+fn WorkspaceRoot() -> impl View {
+    let route = use_router(Route::Home);
+    let session = use_resource(|| async { Session::restore().await });
+    let notifications = use_service::<Notifications>();
+
+    view! {
+        provide::<NotificationsContext>(notifications.clone()) {
+            provide::<ThemeContext>(Theme::dark()) {
+                match session.read() {
+                    Pending => view! { ProgressSpinner(label = "Restoring session...") {} },
+                    Ready(session) => view! {
+                        provide::<SessionContext>(session?) {
+                            WorkspaceShell(route = route) {}
+                        }
+                    },
+                }
+            }
+        }
+    }
+}
+
+#[component]
+fn WorkspaceShell(route: Signal<Route>) -> impl View {
+    let session = use_context::<SessionContext>();
+    let notifications = use_context::<NotificationsContext>();
+
+    use_effect(move || {
+        if !session.is_authenticated() {
+            notifications.info("Signed in as guest");
+        }
+    });
+
+    view! {
+        row(fill = true) {
+            block(
+                role = LandmarkRole::Navigation,
+                width = 280,
+                gap = 12,
+                padding = 20,
+            ) {
+                BrandMark() {}
+                NavLink(route = Route::Home, active = route.is(Route::Home)) { "Home" }
+                NavLink(route = Route::Projects, active = route.is(Route::Projects)) { "Projects" }
+                NavLink(route = Route::Settings, active = route.is(Route::Settings)) { "Settings" }
+            }
+
+            block(fill = true, padding = 20) {
+                match route.get() {
+                    Route::Home => view! { HomeScreen() {} },
+                    Route::Projects => view! { ProjectsScreen() {} },
+                    Route::Settings => view! { SettingsScreen() {} },
+                }
+            }
+        }
+    }
+}
+
+#[component]
+fn HomeScreen() -> impl View {
+    let theme = use_context::<ThemeContext>();
+
+    view! {
+        column(fill = true, gap = 16) {
+            text(role = TextRole::Heading(1), size = 30, weight = FontWeight::Semibold) {
+                "Workspace"
+            }
+            text(color = theme.muted_text()) {
+                "Context should be keyed by provider identity, not only by value type. That allows \
+                 multiple providers for the same `T` to coexist in the tree while descendants borrow \
+                 the correct value by asking for a specific provider marker."
+            }
+        }
+    }
+}
+
+#[component]
+fn ProjectsScreen() -> impl View {
+    view! {
+        EmptyState(title = "Projects go here") {
+            "This screen exists only to show route switching and app-level composition."
+        }
+    }
+}
+
+#[component]
+fn SettingsScreen() -> impl View {
+    view! {
+        column(gap = 12) {
+            text(role = TextRole::Heading(2), size = 24, weight = FontWeight::Semibold) {
+                "Settings"
+            }
+            toggle(label = "Use reduced motion", value = Preferences::reduced_motion()) {}
+            toggle(label = "Use system theme", value = Preferences::system_theme()) {}
+        }
+    }
+}
+
+#[context_provider(Theme)]
+struct ThemeContext;
+
+#[context_provider(Session)]
+struct SessionContext;
+
+#[context_provider(Notifications)]
+struct NotificationsContext;
+
+struct Session;
+struct Notifications;
+struct Theme;
+struct Preferences;
+
+#[derive(Clone, Copy)]
+enum Route {
+    Home,
+    Projects,
+    Settings,
+}
+
+impl Session {
+    async fn restore() -> ruin::Result<Self> {
+        Ok(Self)
+    }
+
+    fn is_authenticated(&self) -> bool {
+        false
+    }
+}
+
+impl Notifications {
+    fn info(&self, _message: &str) {}
+}
+
+impl Theme {
+    fn dark() -> Self {
+        Self
+    }
+
+    fn muted_text(&self) -> Color {
+        Color::rgb(0x94, 0xA3, 0xB8)
+    }
+}
+
+impl Preferences {
+    fn reduced_motion() -> bool {
+        false
+    }
+
+    fn system_theme() -> bool {
+        true
+    }
+}